The present invention relates to a device for cutting a web, more particularly, to a cutting device utilizing a semitubular, or partially tubular, rotary cutting blade, and even more particularly to a hand-held scissors utilizing a semitubular rotary cutting blade.
Conventional cutting devices exist in a variety of forms designed for cutting relatively thin webbing such as paper, cloth, plastic sheeting, or metal foils. Generally, these devices utilize a pair of blades that progressively pass over each other to cut web inserted therebetween. Typically, both blades are flat and define cutting edges that can be straight or curved, with the contour of the two cutting edges corresponding fairly closely. The two blades are typically secured to each other in one of two configurations to accomplish a progressive cut.
In the first configuration, the two blades pivotally joined together. One example of this first configuration exists in conventional hand-held scissors, in which the blades are pivotally secured together intermediate their ends. The blades have opposing cutting ends and opposing loop-shaped handle end. When the handle ends are pressed together, the blades gradually pass over each other to cut a web inserted therebetween. However, this design results in the cutting force decreasing as the cut progresses due to the loss of leverage as the handle ends are drawn together, i.e., the location of the cut moves further away from the pivot point of the blades, making it difficult to complete a cut through thicker webbing.
Another example of this first lever type cutting device configuration is found in standard table mounted paper cutters. A first cutting edge is secured along one side of a flat base, and a second cutting edge is secrued to a lever that is in turn pivotally secured to the base adjacent the first cutting edge. The lever is depressed downwardly towards the base to cause the second cutting edge to gradually pass over the first cutting edge, cutting a web inserted therebetween. This example again exhibits a reduction of cutting force as the cut progresses.
The second conventional cutting device configuration involves the slidable mounting of a movable blade spaced away from and parallel to a first stationary blade, such as in a guillotine-type cutting device. In such a device, the stationary blade is secured along one edge of a base, and the movable blade is slidably secured directly above and parallel to the stationary blade. Typically, the cutting edge on the movable blade is angled with respect to the cutting edge of the stationary blade. When the movable blade is lowered towards the base, the movable cutting edge passes progressively over the stationary cutting edge. This type of device results in a cut being made with uniform cutting force the width of the web, overcoming the limitation of lever type cutters. However, the device is more complex than lever type cutters, increasing the expense of its manufacture, and making it cumbersome for use as a hand-held device. In addition, the parallel opposed facing of the blades does not result in the increased leverage occasioned by lever-type devices, requiring a greater force to cut a given piece of webbing.
An additional limitation of the above-described conventional cutting devices is the exposure of the stationary and movable cutting blades, resulting in a safety hazard should the cutting blades slip relative to the web or a user's fingers happen to be inserted between the blades during cutting.